Various technologies are under consideration for recovering tritium from water and hydrocarbons since tritium will need to be recovered from these impurities for environmental and economic reasons.
One such technology includes a palladium membrane reactor (PMR). The PMR is a combined hydrogen permeator and catalytic reactor. Shift catalysts are used to foster reactions such as water-gas shift, H.sub.2 O+CO.fwdarw.H.sub.2 +CO.sub.2, and methane steam reforming, CH.sub.4 +H.sub.2 O.fwdarw.3H.sub.2 +CO. Due to thermodynamic limitations these reactions only proceed to partial completion. Thus, a Pd/Ag membrane which is exclusively permeable to hydrogen isotopes is incorporated into the reactor. By maintaining a vacuum on the permeate side of the membrane, product hydrogen isotopes, are removed, enabling the reactions to proceed more fully toward completion.
In "Method For Simultaneous Recovery Of Hydrogen From Water And From Hydrocarbons," U.S. Pat. No. 5,525,322, which issued to R. Scott Willms on Jun. 11, 1996, a palladium membrane utilized in cooperation with a nickel catalyst at about 500.degree. C. has been found to simultaneously drive the water gas shift, steam reforming and methane cracking reactions to substantial completion by removing the product hydrogen from mixtures of water and hydrocarbons. In addition, ultrapure hydrogen is collected, thereby eliminating the need for additional product processing. Experiments were conducted at simulated DT fusion reactor exhaust conditions. Decontamination factors (DF=inlet tritium/outlet tritium) were found to be in the 150-400 range. A Ni/.gamma.-Al.sub.2 O.sub.3 catalyst was employed but was found to be unstable under certain conditions in the PMR environment. Pellets tended to break up ink) fine particles, especially when coking occurred. Moreover, for significant flows of exhaust gases, a single-stage reactor would require large permeator areas and pumping capacities to enable the reactions to proceed to levels sufficiently low for environmental release of the retentate stream.
Accordingly, it is an object of the present invention to simultaneously recover hydrogen from water and from hydrocarbons without requiring large pumping capacity.
It is another object of the invention to identify a stable catalyst for simultaneously recovering hydrogen from water and from hydrocarbons.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.